Choose the correct match-
A)Gama line in Lyman series in H--UV
B)Beta line in Balmer series in He+--UV
C)Delta line in Balmer series in H--visible
D)Delta line in Paschen series in H--infrared
Answer is all the options are correct. I have already asked this question and expert told me how to solve it but his question is new to me and I have no idea about what the wavelength must be to be in which series. So pls solve them. thanks!

Lyman series is transition from n=1 to higher orbits.
Alpha line is the first transition, i.e from n=2 to n=1, beta is from n=3 to n=1. gamma is from n=4 to n=1 and so on.....
Balmer ​series is transition from n=2 to higher orbits.
​Alpha line is the first transition, i.e from n=3 to n=2, beta is from n=4 to n=2, gamma is from n=5 to n=2 and so on......
Paschen series is transition from n=3 to higher orbits.
​​Alpha line is the first transition, i.e from n=4 to n=3, beta is from n=5 to n=3, gamma is from n=6 to n=3 and so on......

We can find the wavelength corresponding to these transitions by applying the formula:
1λ=R(1n'2-1n2)n'=lower enery shelln= higher energy shell

a) Lyman-alpha is wavelength corresponding to  n=2 to n=1
1λ=RH(112-122)      =1.09×107 m-1 ×(0.75)=8.175×106 m-1λ=0.122×10-6 ×109 nm=0.122×103 = 122 nm
See that this Lyman series lines is in UV region (less tan 400 nm).

b) Beta line in Balmer series in Heis line corresponding to n=4 to n=2.
Rydberg constant, R for He is 4 times (Z2​ and Z=2 for He) the Rydberg constant of Hydrogen. 
1λ=RHe(122-142)      =4×1.09×107 m-1 ×(0.1875)=8.175×106 m-1λ=0.122×10-6 ×109 nm=0.122×103 = 122 nmIf for hydrogen then wavelength would have been 4×122 = 488 nm that falls in visible region.
Beta line in Balmer series in H is in visible region but for He+ the value of Z2 is 4, so the wavelength is four times shorter than the Balmer series of H atom and hence it lies in UV region.

c) Delta line in Balmer series in H can be calculated similarly:
1λ=RH(122-162)    λ =410.2 nm (visible region)

d) Delta line in Paschen series in H
1λ=RH(122-172)    λ =1005 nm (infra red region)

Hope that's clear now.

 

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